<!DOCTYPE html>
<html lang="en" reftest-async-scroll>
<meta charset="utf-8">
<title>Make sure the scrolled layer is opaque even if the scrolled area is fractional</title>

<style>

body {
  margin: 0;
}

.scrollbox {
  margin: 50px;
  width: 200px;
  height: 200px;
  overflow: auto;

  /* Make the background "non-uniform" so that the scrolled layer does not
   * pull up a background color. */
  background: linear-gradient(to bottom, white, transparent);
}

.scrolled-contents {
  height: 300.2px;
  background-color: lime;
  box-sizing: border-box;
  border: 1px solid lime;
}

.transparent-overlap-of-fractional-edge {
  margin: -10px 20px 0;
  height: 40px;
  background-color: rgba(0, 0, 255, 0.5);
}

</style>

<body>

<div class="scrollbox"
     reftest-displayport-x="0" reftest-displayport-y="-100.2"
     reftest-displayport-w="200" reftest-displayport-h="300.2"
     reftest-async-scroll-x="0" reftest-async-scroll-y="0">
  <div class="scrolled-contents">
    <div class="transparent-overlap-of-fractional-edge reftest-opaque-layer">
      <!-- This element has the magic "reftest-opaque-layer" class which
           constitutes the actual test here. -->
    </div>
  </div>
</div>

<script>

document.querySelector(".scrollbox").scrollTop = 100000; /* will end up at 100.2 */

</script>
